506 BOTANICAL GAZETTE [ DECEMBER 
side increases from the base toward the tip, apparently corresponding with 
the degree of irritability to contact. 
During curvature the parenchymatous cells of the concave side decrease 
in size from 20 to 40 per cent. of their original volume, and become irregu- 
larly globoid or ovoid; which is to be explained by an increase in the per- 
meability of their protoplasts, with a consequent extrusion of water into the 
intercellular spaces, and a release of their stretching tension exerted upon 
their walls, the elastic contraction of which causes the resultant curvature.— 
Wek. M: 
Dr. Emit Knoseavucu. the German translator of Warming’s Geographical 
Botany, has published from Tiibingen a paper upon the ‘“ Ecological anatomy 
of the woody plants of the South African evergreen bush-region.” A review 
by Dr. E. Roth® gives a brief summary of the results. The rainy winters 
and dry summers of the Cape Colony region result in a peculiar vegetation, 
in which dwarf shrubs dominate, both in species and individuals, trees being 
almost wholly absent. The woody plants are first treated, as, on account of 
their long duration, they show best the influence of external conditions upon 
vegetation, notably their adaptation to withstand drought. The anatomy of 
the leaves is especially considered, as they show most clearly these influences. 
The many evidences of a direct adaptation of the South African woody plants 
are enumerated as follows: (1) lignification; (2) evergreen habit; (3) dwarf 
growths, associated with thick branching, small branches, very short inter- 
nodes and small leaves; (4) leaves more or less densely aggregated ; (5) 
leaves more or less erect on the branches, thus avoiding direct rays of the 
sun at midday; (6) leaves with very small cross-section; (7) small leaf sur- 
face; (8) ericoid, pinoid, or involute leaves; (9) thick outer epidermal walls; 
(10) inner epidermal walls mucilaginous, swelling more or less when water is 
taken up; (11) epidermal cells of large capacity, allowing considerable water 
storage ; (12) leaf symmetry dorsiventral and radial; (13) long palisade cells ; 
(14) spongy mesophyll much less open than in mesophytes; (15) a brown 
coloring matter, probably tannin, present in the strongly illuminated periph- 
eral portions of the leaves, forming a protection against too strong light; 
(16) presence of hairs on the furrowed side of ericoid leaves and of the dorsi- 
ventral involute leaves to protect against excessive transpiration. Any given 
species ordinarily has but few of the above characteristics, and all plants do 
not have them developed to the same degree. Another set of characters is 
not general, but is confined to certain groups of plants. These special 
characters are given as follows: (1) depression of stomata; (2) hypodermal 
aqueous tissue ; (3) internal aqueous tissue ; (4) sclerenchyma, which increases 
the rigidity of the aqueous and chlorophyll tissues; (5) oil reservoirs; (6) bud 
scales.—H. C. C. 
3 Bot. Centralb. 67: 391. 1896. 
